Change is in the air with strong solar effect and the beginning of a warming trend in the forecast. These two factors will begin to undermine stability on Wednesday.
Confidence
Moderate - Timing or intensity of solar radiation is uncertain
Weather Forecast
Wednesday: A mix of sun and cloud. Light west winds. Alpine temperatures rising to around -2 during the day, increasing in the evening with the onset of an alpine temperature inversion.Thursday: A mix of sun and cloud with some low valley cloud due to a strong alpine temperature inversion. Light west winds. Freezing level rising from 2700 to 3300 metres over the day with alpine temperatures around +4. Cooler at lower elevations.Friday: Mainly sunny with some valley cloud due to lingering alpine temperature inversion. Light west winds. Freezing level to 3300 metres with alpine temperatures around +6.
Avalanche Summary
Reports from Monday showed a couple of wind slabs releasing naturally and with ski cutting to Size 1.5 in the Fernie area. On Sunday, avalanche control with explosives triggered numerous size 1 dry loose avalanches above 1900 m from northeast aspects. Please submit your observations to the Mountain Information Network (MIN).
Snowpack Summary
Recent winds have been redistributing loose snow at higher elevations and forming wind slabs on leeward slopes and terrain features. Below the surface, 40-60 cm of accumulated storm snow now sits above the crust that formed a week ago. The buried crust is supportive and approximately 25 cm thick. It extends from 1600 m to mountain top elevations on all aspects. The bond of our recent storm snow to this crust is expected to be strengthening gradually and it has produced hard, resistant results in recent snowpack tests. Below this interface, the snowpack is moist to ground. The average snowpack depth at treeline is 60-80 cm while a deeper snowpack exists in the alpine.
Problems
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.